Clinical laboratories use various types of quality control rules to identify performance issues with the laboratory instruments used to provide laboratory testing services. A common practice is to run a laboratory test on quality control specimens and evaluate the test results against one or more quality control rules to determine whether the test results are “in control” or “out of control.” For example, if the quality control rule for a laboratory test is 1:3s (which means a range of 3 laboratory standard deviations around the laboratory mean) and the laboratory mean is 10 and the laboratory standard deviation is 1, then all test results falling between 7 and 13 would be accepted as “in control” and all other test results (e.g., 6 or 14) would be rejected as “out of control.” If the test results are “in control,” the laboratory instrument is deemed to be functioning properly and is thus suitable for testing actual patient specimens. On the other hand, the laboratory instrument is deemed to be malfunctioning if the test results are “out of control.”
Because of the arithmetic complexity of quality control rules, laboratories use computer software to implement the quality control rules for all of the laboratory tests. Typically, the computer software includes a menu screen that allows a user to select one or more quality control rules (from a limited number of quality control rules) to be used in connection with each laboratory test. For example, a menu screen may provide the following available choices of quality control rules: 1:2s, 1:2.5s, 1:3s, 1:3.5s, 1:4s, 1:5s, 3:1s, 4:1s, 7T, 7x, 8x, 9x, 10x, and 12x.
As is known in the art, the 1:2s, 1:2.5s, 1:3s, 1:3.5s, 1:4s and 1:5s quality control rules mean that test results falling outside the range of 2 (or 2.5, 3, 3.5, 4 or 5) laboratory standard deviations around the laboratory mean would be rejected as “out of control.” The 2:2s and (2 of 3):2s quality control rules mean that test results would be rejected as “out of control” when 2 (or 2 out of 3) consecutive test results are either lower than the laboratory mean minus 2 laboratory standard deviations, or, are higher than the laboratory mean plus 2 laboratory standard deviations. The R4s quality control rule means that test results would be rejected as “out of control” when there is a range exceeding 4 laboratory standard deviations between 2 test results.
Also, the 3:1s and 4:1s quality control rules mean that tests results would be rejected as “out of control” when there are 3 (or 4) test results on the same side of the laboratory mean plus 1 laboratory standard deviation. The 7T quality control rule means that test results would be rejected as “out of control” when there is a 7 point trend (either up or down) of the test results. Finally, the 7x, 8x, 9x, 10x, and 12x quality control rules mean that test results would be rejected as “out of control” when there are 7 (or 8, 9, 10 or 12) consecutive test results on the same side of the laboratory mean.
It can be appreciated that the available choices of quality control rules provided on the menu screen (e.g., 1:2s, 1:2.5s, 1:3s, 1:3.5s, 1:4s, 1:5s, 3:1s, 4:1s, 7T, 7x, 8x, 9x, 10x, and 12x) are very discrete and fairly limited. For example, a user cannot select a 1:2.75s quality control rule or a 5:1s quality control rule for a laboratory test because those quality control rules are not offered or implemented. Thus, the user's only option is to select the best of the available quality control rules for a particular laboratory test.